British insects: the families of Coleoptera
British insects: the families of Coleoptera |
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Clavigeridae, Staphylinidae-Pselaphinae.
General appearance. 1–3 mm long. Body length/maximum body width 1.5–10. Elytral length/pronotal length 0.9–2. Base of prothorax not or scarcely narrower than the combined elytral bases, or distinctly narrower than the combined elytral bases. Greatest prothoracic width not narrower or only slightly narrower than the greatest elytral width, or distinctly narrower than greatest elytral width. Beetles oval to elongate; conspicuously necked; somewhat waisted to conspicuously waisted; reddish or yellowish. Upper surfaces of body glabrous or subglabrous, or non-glabrous; not bristly; exhibiting scales or scale-like setae, or with neither scales nor scale-like setae.
Detailed morphology. Inclination of the head slight to strong. Eyes strongly protuberant, or not strongly protuberant; bristly, or without bristles; coarsely facetted. Ocelli present; paired. Antennae very short to long, but not exceeding the insect’s head to tail length; thick, (3–)5 segmented (commonly), or 6–10 segmented, or 11 segmented; clubbed. Antennal clubs 3 segmented. Antennal insertions visible from above, or hidden from above; ‘countersunk’ within saucer-like fossae, or not in fossae. Mandibular prosthecae present but reduced, or absent. Prothorax about as long as wide. Pronotal length/maximum pronotal width 0.85–1.3. Prothorax at its widest markedly narrower than the adjoining part of the abdomen to not markedly narrower than the adjoining part of the abdomen. Prothorax without notopleural sutures. Metaventrite without a transverse groove. Tarsal segmentation formula 3, 3, 3, or 0–2, 3, 3. The tarsi with a tiny basal segment that is hard to detect, or without ‘hidden’ segments. The front tarsi present and well developed, or reduced or absent; front tarsi when present, with as many segments as the mid-tarsi, or with one segment fewer than the mid-tarsi; front tarsi 3-segmented (or fewer). Mid-leg tarsi 3-segmented; trimerous. The claws of the mid-leg tarsi not appendaged. The claws of the mid-leg tarsi simple; without an associated empodium. Hind tarsi with as many segments as the mid-tarsi; 3-segmented. Elytral length/maximum width across the elytra 0.6–1.1. Elytra meeting along the length of the mid-line; short, exposing several terminal abdominal tergites (leaving most of the abdomen exposed, cf. Staphylinidae); exposing at least one but fewer than three complete abdominal tergites to at least three complete abdominal tergites; truncate. Scutellary striole absent. Wings well developed, or absent or much reduced. Exposed abdominal sternites 5, or 6; all articulated and movable. Abdominal segment 8 with apparently functional spiracles, or apparently without functional spiracles.
Adult habitat, ecology. Predacious (especially on Springtails); in decaying plant material, in rotting wood, under bark, on shed fur or feathers, and under stones (also in ants’ nests).
Larvae. Larvae predacious; in decaying plant material, in rotting wood, in or under bark, in shed fur or feathers, and under stones (and in ants' nests).
Classification. Suborder Polyphaga; Infraorder Staphyliniformia; Superfamily Staphilinoidea.
Worldwide and British representation. About 9000–10000 species worldwide (especially diverse in the tropics). 51 species in Britain; genera in Britain 19; Batrisodes, Bibloporus, Bibloplectus, Brachygluta, Bryaxis, Claviger, Bythinus, Euplectus, Pselaphaulax, Rybaxis, Trichonyx, Tychus, etc. E.g., Bryaxis puncticollis (Punctured-necked Pselaphus); Trichonyx sulcicollis (Carlisle Pselaphus).
General comments. Adults readily distinguished from Staphylinidae by the dorsoventrally inflexible abdomen, and in having both the antennae and the palps clubbed..
Illustrations. • Bryaxis puncticollis (Punctured-necked Pselaphus: B. Ent. 422). • Bryaxis puncticollis (details, B. Ent. 422). • Bryaxis puncticollis: B. Ent. 422, legend+text. • Bryaxis puncticollis: B. Ent. 422, text cont.. • Trichonyx sulcicollis (Carlisle Pselaphus: B. Ent. 315). • Trichonyx sulcicollis: B. Ent. 315, legend+text. • Trichonyx sulcicollis: B. Ent. 315, text cont.. • Brachygluta, Bryaxis, Bythinus, Pselaphaulax, Reichenbachia, Rybaxis, Trissemus, Trychobythinus: Fowler 3, 77 (1889). • Fowler 3, 77 (1889): original legend.. • Batrisodes, Bibloplectus, Bibloporus, Euplectus, Trichonyx, Trimium (with Ptiliidae): Fowler 3, 78 (1889). • Fowler 3, 78 (1889): original legend.. • Claviger testaceus and Pselaphus heisei, with Scydmaenidae: Fowler 3, 76 (1889). • Fowler 3, 76 (1889): original legend.. • Amauronyx maerkeli, Claviger, Euplectus (2 spp.), Plectophloeus (with Triplax, Coccinellidae and Phalacridae): Fowler Suppl. 12, 1913. • Fowler Suppl. 12, 1913: original legend..
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the families of Coleoptera. Version: 2nd January 2012. http://delta-intkey.com’.
